fix(date-value): do not submit in case of period button (DEV-373)

src/app/workspace/resource/values/yet-another-date-value/date-value-handler/date-value-handler.component.html

@@ -7,7 +7,7 @@
 
         <button mat-button class="toggle-period-control" [disabled]="!startDate.value"
             [matTooltip]="(isPeriodControl.value ? 'Delete end date' : 'Add end date')" matTooltipPosition="above"
-            (click)="togglePeriodControl()">
+            (click)="togglePeriodControl($event)">
             <mat-icon *ngIf="!isPeriodControl.value">keyboard_tab</mat-icon>
             <mat-icon *ngIf="isPeriodControl.value">remove</mat-icon>
         </button>

src/app/workspace/resource/values/yet-another-date-value/date-value-handler/date-value-handler.component.ts

@@ -300,7 +300,8 @@ export class DateValueHandlerComponent extends _MatInputMixinBase implements Con
         this.onChange(this.value);
     }
 
-    togglePeriodControl() {
+    togglePeriodControl(ev: Event) {
+        ev.preventDefault();
         this.isPeriodControl.setValue(!this.isPeriodControl.value);
     }